A lithium ion secondary battery has a capacity density higher than that of the other secondary batteries and is capable of an operation at high voltages, and therefore is used as a power source of information-related equipment, communication equipment, etc., as a secondary battery that can be reduced in size and weight. Further, the development of a lithium ion secondary battery used as a power source of a low-pollution car, such as an electric car and a hybrid car, is progressing.
A lithium ion secondary battery or the lithium secondary battery includes a positive electrode layer and a negative electrode layer, and an electrolyte arranged between the positive electrode layer and the negative electrode layer and including lithium salt. The electrolyte of the lithium ion secondary battery or the lithium secondary battery is formed by a non-aqueous liquid or solid. when a non-aqueous liquid electrolyte is used as an electrolyte, an interface between the positive electrode active material constituting the positive electrode layer and the electrolyte is easily formed, and therefore it is easy to improve the electrical performance, such as an output and an internal resistance, since an electrolyte solution permeates into the inside of the positive electrode layer. The liquid used as an electrolyte solution in the lithium ion secondary battery is generally combustible, and therefore safety is guaranteed by mounting equipment that prevents a short circuit and a device that suppresses a rise in temperature of the battery. On the other hand, in the all-solid battery the whole of which has been made solid by using a solid electrolyte in place of the liquid electrolyte is thought to be excellent in the manufacturing cost and the productivity, since no combustible material is arranged inside the battery, and therefore the safety device can be simplified.
It is known that in an all-solid battery including a fuel cell stack in which a plurality of single batteries is stacked, the electrical characteristics of the all-solid battery are changed by changing a confining pressure that is applied to the stack direction of the fuel cell stack. For example, it is known that one of the confining pressures of the fuel cell stack and the electrical characteristics of the fuel cell stack is detected by changing the confining pressure applied in the stack direction of the fuel cell stack and the confining pressure is controlled based on the detected confining pressure or electrical characteristics.